Mets trainer Ray Ramirez, left, checks out pitcher Jonathon Niese, after he was hit in the right leg by a ball hit by Dodgers Mark Ellis in the third inning. Niese had to leave the game. Photo: Bill Kostroun/New York Post

That’s one tough Mark to erase.

Between the bruise Mark Ellis planted on Jon Niese’s right leg and the damage the Dodgers second baseman inflicted upon Robert Carson and Brandon Lyon, the Mets couldn’t escape Citi Field fast enough Tuesday night.

Ellis knocked out Niese with a comebacker and then pummeled an entire team with two home runs and four RBIs in the Mets’ 7-2 loss before an announced crowd of 21,135.

Niese hobbled from the mound in the third inning and was removed from the game after Ellis’ one-hopper drilled the left-hander in the lower right leg, leaving him with a contusion — X-rays were negative.

Ellis, who hadn’t homered this season, then tormented the Mets’ bullpen. That meant a three-run blast off Lyon in the seventh to snap a 2-2 tie, after Carson had surrendered a solo homer to Ellis in the fifth.

The Mets (9-9) will like their chances of resting the bullpen tonight, when phenom Matt Harvey takes the mound seeking a fifth straight victory to begin the season. But the Mets also have to wonder if Niese will be in position to take his next turn in the rotation, on Sunday against the Phillies.

Niese’s final line included 2 ¹/₃ innings with one run allowed on three hits and three walks. The lefty was coming off consecutive mediocre performances in a victory over the Twins and loss to the Rockies.

Clayton Kershaw was sloppy for the Dodgers, lasting only five innings in which he allowed two earned runs on three hits and four walks, but the Mets couldn’t deliver the knockout punch. Their best chance came in the third, when Marlon Byrd was retired with the bases loaded to end a threat after the Mets had already scored twice.

With it 2-2 in the seventh, Justin Sellers singled for the Dodgers and Juan Uribe walked against Lyon before Ellis cleared the fence in left-center.

Josh Edgin helped further bury the Mets in the eighth, allowing two runs over one-third of an inning. The erratic lefty saw his ERA surge to 10.80 and would seem in jeopardy of losing his roster spot after a fourth straight rough outing.

Ellis stuck it to the Mets in the fifth, with a two-out homer against Carson that made it 2-2. The blast was the 100th career home run for Ellis, whom the Mets had interest in before the 2012 season.

Carson was removed after the homer. All told, the lefty allowed one run on two hits over 2 ¹/₃ innings in his first appearance since arriving from Triple-A Las Vegas.

Kershaw scuffled through the third inning, surrendering two runs to give the Mets a 2-1 lead. Daniel Murphy and David Wright each delivered an RBI single, after Carson and Ruben Tejada walked in succession to begin the rally.

Carson got some defensive help. Murphy and Tejada made consecutive highlight reel plays to retire Andre Ethier and A.J. Ellis starting the fourth, after Tejada made a lunging grab on a Jerry Hairston Jr. line drive to end the third.

Juan Lagares made his major league debut with a single in the seventh inning and became the fifth center fielder the Mets have used this season.

The 24-year-old Lagares was batting .346 with three homers and nine RBIs in 17 games for Las Vegas and is expected to make his first major league start tonight. Kirk Nieuwenhuis was optioned to Triple-A yesterday to create roster space for the new arrival.

“[Lagares] is the future — a great defender,” manager Terry Collins said before the game. “He’s got some power. There are people in this organization who think he’s a better center fielder than Matt den Dekker, which speaks a lot.”